1. Field of the Invention
The present invention relates to an apparatus and method for transmitting/receiving a signal in a signal transmission/reception apparatus of a communication system. More particularly, the present invention relates to an apparatus and method for transmitting/receiving a signal after removing an echo signal in a signal transmission/reception apparatus of a communication system.
2. Description of the Related Art
In a conventional communication system, a signal is transmitted/received through a direct link between a Base Station (BS) and a Mobile Station (MS). However, in the conventional communication system, a location of the BS is fixed, so it is difficult to supply an effective communication service when there is a shadow region in a service area or when there is significant variation of a channel state. Therefore, in the conventional communication system, a Relay Station (RS) is used for amplifying a BS signal and extending a service area of a BS.
The conventional communication system can extend a cell service area and provide a channel with a better channel state to an MS using the RS. Further, the BS can provide a faster data channel to an MS using the RS in a cell boundary region that experiences a poor channel state.
FIG. 1 is a diagram illustrating a structure of a conventional communication system using an RS.
Referring to FIG. 1, the conventional communication system includes a BS 110, an RS 130, and an MS 150.
The BS 110 can directly transmit data to the MS 150, and can transmit data to the MS 150 using the RS 130. The MS 150 can directly transmit data to the BS 110, and can transmit data to the BS 110 using the RS 130.
The RS 130 amplifies a signal received from the BS 110, and transmits the amplified signal to the MS 150. The RS 130 amplifies a signal received from the MS 110, and transmits the amplified signal to the BS 150. Further, the RS 130 includes at least one antenna for transmitting/receiving a signal.
Referring to FIG. 1, it will be assumed that the RS 130 includes two antennas, i.e., a transmission antenna for transmitting a signal and a reception antenna for receiving a signal.
Because the RS 130 transmits/receives signals, a signal transmitted through the transmission antenna of the RS 130 can be received by the reception antenna of the RS 130. The signal transmitted through the transmission antenna of the RS 130 that is received by the reception antenna of the RS 130 is referred to as an “echo signal”.
The echo signal results in the occurrence of oscillation in the RS 130. In addition, the signal received through the reception antenna is distorted due to the echo signal. When the signal received through the reception antenna is distorted, the quality of a signal transmitted by the RS 130 is decreased.
Therefore, there is a need for a signal transmission/reception apparatus that removes an echo signal in order to prevent a decrease in quality of a transmission signal due to the echo signal in the conventional communication system.